Tool for cutting grooves



Jan. 11, 1944. scHlLLlNG 2,338,972

TOOL FOR CUTTING GROOVES Filed March 19. 1941 Patented Jan. 11, 1944 UNIT TQOL FOR CUTTING GROOVES ttmar Schilling, Greifenstein-on-the-iDanube,

Germany; vested in the Alien Property Custodian Application March 19, 1941, Serial No. 384,197 In Germany February 21, 1940 2 Claims.

My invention relates to improvements in tools for chiselling out-grooves or channels in the surface of hard layers say of wood or especially of brickwork, these grooves or channels being destined to receive conduits for electric current, gas, water or the like and has for its object the provision of a tool, enabling a more expeditious and simpler production of such grooves or channels by simultaneously cutting out both longitudinal side walls of such grooves or channels.

A further object of the invention is to provide a tool adapted to produce grooves or channels with difierent inner width, using the same constituent parts of such a tool.

Heretofore chiselling out of such grooves has been done with a chisel of usual length of its cutting edge along two parallel marking lines by repeated and successive putting of the chisel with its cutting edge on the marking line, driving it in and removing it out of the brickwork, the chiselling out being done first along one marking line and thereafter along the other line whereas the tool of the invention enables simultaneous cutting along two parallel lines.

The tool according to the present invention consists in essence of a head provided with a handle and adapted to receive the blows of an iron or a wooden hand hammer, this head being provided with a pair of jaws in the shape of chisels or knives the cutting edges of which are parallel to and distant from each other.

The cutting edges of these chisels or knives are preferably essentially longer than those of chisels usually employed for work of this kind.

In the preferred embodiment of the invention 1 the chisels o1 knives are removably fixed unto the head and thereby may be substituted by another pair of chisels which have diiferent shape and dimension. Furthermore each chisel of a pair thereof is interchangeable for the other similarly shaped chisel or for a chisel of another shape or dimension. By such an arrangement it is feasible to produce grooves or channels of different breadth not only by means of the same head by using pairs of chisels of difierent shape or by exchanging one chisel of special shape for the other of the same special shape, but also by using pairs of similarly or differently shaped chisels in combination with heads of varied dimensions.

In most cases it is sufficient to provide for the preferred embodiment of a tool in which the chisels have their cutting edges somewhat distant from the middle plane of such part of the chisel which serves to connect it to the head. In this case when turning one or both of the chisels for it is possible to obtain besides the normal position one or two additional positions of the chisels in which the distance between the parallel cutting edges is longer or smaller. Such a tool enables chiselling out of grooves of three different widths with the same head and with a pair of similarly shaped chisels.

The preferred shape of the chisels in which this latter has very long cutting edges enables to carry out chiselling out in the manner of a drawn out by placing the cutting edges somewhat obliquely to the wall surface and displacing the tool in longitudinal direction simultaneously applying blows unto the head. In this manner, on the one hand, those parts of the chisel which have already entered the wall surface furnish a guide to the progressive movement of the tool and, on the other hand, a complete removal and a renewed putting of the chisels for applying blows is rendered unnecessary.

In the drawing one embodiment of the tool according to the invention is illustrated, Fig. 1 being a view, Fig. 2 a section on the line A-B of Fig. 1; Fig. 3 is an illustration of a chisel removed from the head.

The tool consists of a head I of an essentially parallelepipedic shape with a curved upper blow surface 2 and a handle 3. Unto the undercut side faces 4, 5 of the head apply the backs or clamping parts 6 ofchisels or knives l, 8, which are fixed thereon by screw-bolts 9. The chisels or knives are provided either with an eye or with a slot l0 through which passes the screw bolt 9 having a screw nut l2. The provision of a slot has an advantage in over'an eye to facilitate applying the chisels unto the head I.

The chisels have preferably the contour of a rectangle (Fig. 3) and show an enlarged back or clamping part 6 and a tapering extension thereof or stem ending in the cutting edge l3. This cutting edge is excentrically disposed to, i. e., somewhat distant from the parallel to the longitudinal plane of symmetry C-D of the clamping part as illustrated in Fig. 2 in dotted lines. When turning one or both of the chisels on the axis of symmetry and fixing them respectively to the head, their cutting edges furnish three difierent distances a, b, 0 between them so that with one and the same tool of this kind grooves or channels of three different breadths may be made.

The tool is held by its handle and placed unto the wall or layer to be chiselled out in such a manner that its cutting edges are somewhat oblique to the wall surface. In this position the tool is intermittently drawn longitudinally along a marking line on the wall simultaneously applying blows unto the head by means of a hand hammer.

Those parts of the chisels which have entered the wall furnish a guide and thereby facilitate the drawing of the tool along the marking lines and cut out both side walls of the groove.

If desired one of the chisels may have a somewhat minor dimension in height of its stem in order to reduce the depth of the out which is produces.

What I claim is: v

1. A tool for chiselling out grooves in the surface of hard materials, comprising a head member the top of which is adapted to receive blows from a hammer, an elongated handle extending laterally from one end of the head member, and

a pair of chisels both detachably fastened to opposite sides of the head member and extending in substantially parallel relation, the upper edges of said chisels being laterally offset relative to the plane of the chisels, the upper ends of the chisels being adapted to fit within correspondingly shaped recesses formed in the sides of the head member and the lower edges of the chisels sharpened to form cutting edges.

2. A tool for chiselling out grooves in the surface of hard materials, comprising a head member comprising a generally rectangular block of metal the top of which is adapted to receive blows from a hammer, an elongated handle extendin laterally from one end of the head member, and a pair of chisels both detachably fastened to opposite sides of the head member, said chisels each comprising a generally rectangular metal plate having it upper edge increased in thickness so as to provide a generally rectangular boss having parallel fiat sides and its lower edge being sharpened to form a cutting edge, said boss being laterally offset with respect to the chisel, said head member being recessed to provide seats for receiving the bosses of the chisels with corresponding faces of the chisels either in opposed, reversed or corresponding position to vary the spacing between the cutting edges.

OTTMAR SCHILLING. 

